The present invention relates to a combustion-type power tool, and more particularly, to such power tool capable of driving a fastener such as a nail, an anchor, and a staple into a workpiece.
A combustion type power tool provides high operability in comparison with a pneumatically operated power tool requiring a compressor and a hose. In a conventional combustion-type driving tool such as a nail gun, a gaseous fuel injected into a combustion chamber is ignited to cause gas expansion in the combustion chamber, which in turn causes a linear momentum of a piston. By the movement of the piston, a nail is driven into a workpiece. In order to improve combustion, a motor having a motor shaft is supported to a cylinder head, and a fan connected to the motor shaft is disposed in the combustion chamber for agitating a combustible gas. Further, a bumper is disposed to absorb kinetic energy of the piston moving toward the workpiece. Such conventional combustion-type driving tool is disclosed in U.S. Pat. No. 4,483,280.
The motor is reciprocally moved relative to the cylinder head in the sliding direction of the piston at the explosion timing and bumping timing of the piston against the bumper. To this effect, a predetermined gap is provided between the motor shaft and the cylinder head.